A distinct subtype of "metatropic dysplasia variant" characterised by advanced carpal skeletal age and subluxation of the radial heads.
BACKGROUND
"Metatropic dysplasia variants" are a group of bone dysplasias whose skeletal abnormalities are similar to, but milder than, those of classical metatropic dysplasia. The genetic and phenotypic heterogeneity has not been thoroughly elucidated.


OBJECTIVE
The objective was to designate a distinct subtype of these metatropic dysplasia variants.


METHODS
The subjects were four Japanese patients, two sporadic cases and two siblings, who all had identical skeletal changes. The radiological features in these patients were compared with those of previously reported metatropic dysplasia variants.


RESULTS
Moderate platyspondyly with pear-shaped and/or anterior-tongued vertebral bodies, halberd pelvis, and dumbbell deformity of the tubular bones were regarded as hallmarks of metatropic dysplasia variants. The peculiar skeletal change in our patients was advanced carpal skeletal age in childhood, unlike most patients reported as metatropic dysplasia variants who manifest delayed carpal ossification. Another hallmark was congenital dislocation of the radial heads. A description of a patient with similar skeletal changes was found in the literature.


CONCLUSIONS
These patients are considered to represent a distinct subgroup of metatropic dysplasia variants. It remains unknown whether the present siblings represent an autosomal recessive trait or an autosomal dominant trait with germinal mosaicism related to increased paternal age.
Nishimura
G
G
Department of Radiology, Dokkyo University School of Medicine, 880 Kitakobayashi, Mibu Shimotsuga-gun, Tochigi-ken 321-02, Japan.
Satoh
M
M
Aihara
T
T
Aida
N
N
Yamamoto
T
T
Ozono
K
K
D000015:Abnormalities, Multiple; D000365:Age Determination by Skeleton; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D010009:Osteochondrodysplasias / Q000145:classification / Q000000981:diagnostic imaging* / Q000235:genetics; D011884:Radius / Q000002:abnormalities